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Date: Fri, 14 May 2010 20:40:02 -0400 (EDT)
From: "sam rash (JIRA)" <jira@apache.org>
To: hdfs-issues@hadoop.apache.org
Subject: [jira] Commented: (HDFS-200) In HDFS, sync() not yet guarantees
 data available to the new readers
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    [ https://issues.apache.org/jira/browse/HDFS-200?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12867762#action_12867762 ] 

sam rash commented on HDFS-200:
-------------------------------

sorry, should be easy to make a unit test, but i didn't have time.  the case is that any lease that expires and has more than one path associated with it will throw exceptions.  the leaseManager 
calls internalRelease(lease, src) and expects only the lease for src to be removed by the call (hence it does its own loop on all the paths for a lease).  However, with hdfs-200, this function removes
*all* paths for the lease, not just the specified one.  internalReleaseLeaseOne does just the single path.

if I get a minute, I can make such a test case quickly and update the patch w/it


> In HDFS, sync() not yet guarantees data available to the new readers
> --------------------------------------------------------------------
>
>                 Key: HDFS-200
>                 URL: https://issues.apache.org/jira/browse/HDFS-200
>             Project: Hadoop HDFS
>          Issue Type: New Feature
>            Reporter: Tsz Wo (Nicholas), SZE
>            Assignee: dhruba borthakur
>            Priority: Blocker
>         Attachments: 4379_20081010TC3.java, checkLeases-fix-1.txt, fsyncConcurrentReaders.txt, fsyncConcurrentReaders11_20.txt, fsyncConcurrentReaders12_20.txt, fsyncConcurrentReaders13_20.txt, fsyncConcurrentReaders14_20.txt, fsyncConcurrentReaders15_20.txt, fsyncConcurrentReaders16_20.txt, fsyncConcurrentReaders3.patch, fsyncConcurrentReaders4.patch, fsyncConcurrentReaders5.txt, fsyncConcurrentReaders6.patch, fsyncConcurrentReaders9.patch, hadoop-stack-namenode-aa0-000-12.u.powerset.com.log.gz, hdfs-200-ryan-existing-file-fail.txt, hypertable-namenode.log.gz, namenode.log, namenode.log, Reader.java, Reader.java, reopen_test.sh, ReopenProblem.java, Writer.java, Writer.java
>
>
> In the append design doc (https://issues.apache.org/jira/secure/attachment/12370562/Appends.doc), it says
> * A reader is guaranteed to be able to read data that was 'flushed' before the reader opened the file
> However, this feature is not yet implemented.  Note that the operation 'flushed' is now called "sync".

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